Understanding infant corpse carrying behaviour in primates could provide clues to how humans perceive death

Among the fascinating behaviours observed in chimpanzees and bonobos, infant corpse carrying is one of the more unusual ones. But mothers will sometimes carry their infants for days, weeks and even months.

One chimpanzee in the Mahale Mountains, Tanzania, was recorded carrying her deceased infant for perhaps as long as 126 days.

Now a study, published in the journal Biology Letters, has explored why this behaviour might vary among primate mothers.

Researchers from the University of Oxford, UK, analysed 83 recorded cases of the behaviour spread across 15 distinct western chimpanzee, eastern chimpanzee and bonobo communities.

“Historically, much of what we know about animals reacting to deceased group members has come from isolated, mostly anecdotal observations rather than structured, cross-site research,” say the study’s authors, Thomas A. Püschel and Reece Hammond.

“So, shedding some light on the drivers of this fascinating behaviour in chimps and bonobos was genuinely very exciting!”

The researchers note that “infant corpse carrying is best explained by maternal attachment and the infant’s cause of death”.

Older infants were carried for longer, with the researchers suggesting that the behaviour may arise as a leftover of prolonged and intensive care – this doesn’t simply ‘switch off’ overnight.

Mothers carried infants for significantly longer following disease-related deaths in comparison to infanticide.

No other cause of death category (such as accidental, injury or premature) showed significant association with the duration of the behaviour.

The scientists note that male primates may kill infants and if mothers continue to carry these infants, they may be exposed to more aggression. Using this interpretation, carrying after disease-related deaths carries less social risk for the mother within the troop.

Clay tablets preserve kisses between ancient deities, while living apes offer clues to a much deeper history. New research has expanded the question from when people first recorded kissing to how the behavior might have evolved.

A 2025 historical review identifies romantic kissing in Sumerian manuscripts dated to approximately 2600–2500 BCE. Separately, a comparative study suggests mouth-to-mouth kissing may have existed in the ancestors of large apes 21.5–16.9 million years ago.

The two findings measure different things. One concerns surviving written evidence. The other reconstructs ancestral behavior statistically, using a broader definition than human romantic kissing.

Neanderthals may have used a sticky substance made from tree bark not only to construct tools but also to treat wounds and fight bacterial infections.

Scientists have discovered that birch tar, a material commonly associated with prehistoric toolmaking, has antibacterial properties that could have made it useful as an ancient form of medicine.

The findings come from a study conducted by researchers at the University of Cologne, the University of Oxford, the University of Liège, and Cape Breton University in Canada.

By recreating techniques believed to have been used by Neanderthals, the team produced birch tar and tested its ability to inhibit harmful bacteria.

Their results suggest that this prehistoric adhesive may have served a second, previously overlooked purpose: helping protect wounds from infection.

The research was published in PLOS One under the title "Antibacterial properties of experimentally produced birch tar and its medicinal affordances in the Pleistocene."

If you are interested in exploring complex topics in deep time, then check out the Before Us Podcast.

Last season, we began to explore the origins of aquatic adaptations. Those episodes began with the earliest current evidence for human interest in aquatic resources ca. 2 million years ago and ended with discussions about when, where, and how people arrived in Sahul (prehistoric Australia) 65,000 years ago.

Our new season started on September 29 with a really awesome episode about the role of storytelling and oral history in the preservation of knowledge within pre-literate societies. Upcoming episodes will crisscross eastern Asia and the North Pacific Rim, before ending with the Peopling of the Americas.

Every episode includes conversations with world-class researchers who simply and clearly lay out the most current research and what it means. We also often include insights from outside of academia, particularly members of indigenous communities from around the world.

It's a show that also considers the people who created our prehistory, So, for example, when we discuss what drift modeling results using super-computers tells us about making over-water voyages to Sahul, we also consider the real-world implications of those voyages, which were undertaken by families that included children. I know from my own experiences that road trips with kids are hard enough. Now, just imagine the motivations of our ancestors tens of thousands of years ago, some of whom risked traveling across open water for days without any guarantee they would reach their destination?

The show is fun, it’s engaging, and it’s also hosted by a pair of professional archaeologists who share a commitment for high-quality science communication. (Full disclosure, I am one of those hosts, having over 20 years of experience studying the origins and development of coastal foraging during the Middle and Late Pleistocene in southern Africa. My co-host is equally experienced. She is a professor of maritime archaeology, specializing in the development of watercraft and the earliest expansions of people from Sundaland to Sahul.)

So, if any of this sounds interesting then check out the show. New episodes air every Tuesday. Our next episode, which airs on Oct 13, features Prof. Christopher Bae who lays out the Asian archaeological and paleoanthropological record during the time that modern humans began to move into the region. The discussion about the taxonomy of the Harbin cranium (H. longi) and the Xujiayao skeletal remains (H. juluenesis) is especially interesting and current.

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The oldest human genome yet sampled from the Americas dates to about 12,800 years ago. Yet the population history reconstructed from that DNA reaches thousands of years further back, offering clues to migrations that left few surviving traces. A genome can preserve clues to older ancestors without recording the location of their migrations.

A review led by Bethany Potter at the University of Kansas argues that existing genetic evidence best fits an initial migration between 20,000 and 14,000 years ago. Published online in Current Opinion in Genetics & Development, it compares migration models with archaeological and environmental evidence.

The conclusion concerns the ancestry represented in sampled ancient people and living Indigenous populations. It does not establish the date of the first human footsteps anywhere in the Americas. Earlier arrivals remain possible, particularly because the genetic record is geographically uneven and missing its earliest chapters.

Fractures once treated as damage from an ancient burial environment may instead record violence against people associated with Egypt’s earliest rulers. A reassessment of 46 preserved skulls from Abydos identified potentially lethal injuries near the time of death in 18 individuals, or 39% of the sample.

The findings strengthen the case for retainer sacrifice, the killing of household or court members to accompany a deceased ruler. They also challenge a century-old claim that these remains showed no evidence of serious trauma. The surviving bones cannot establish every person’s cause of death.

Purdue University anthropologist Roselyn Campbell discusses the reassessment in Frontiers in Environmental Archaeology. The archaeological case study draws on her earlier analyses to examine how forensic advances change interpretations of old collections. It combines skeletal evidence with burial records and photographs.

See also: The study as it was published in the American Journal of Biological Anthropology